Adsorption of alizarin and fluorescein dyes onto palm seeds activated carbon: Kinetic and thermodynamic studies

Activated carbon was prepared from date palm seed using one step procedure with 56.54 % efficiency,2.89 % ash content,781.40 m2 g-1 surface area,711.2 mg g-1 iodine number and the chn analysis gave 69.25 % c,3.91% h and 1.56% n. the ftir spectroscopy revealed o-h,c-h,c=c,c=c and c-o stretching; xrf revealed p,ca,si,s and k as major elements. the influences of agitation time,initial dye concentration,adsorbent dose and temperature were studied in batch experiments. a 57.78% alizarin and 68.40% fluorescein removal were attained within the first 15 min of agitation. kinetic studies showed good correlation coefficient for pseudo-first and pseudosecond order kinetic models. the adsorption data fitted well into langmuir isotherm than freundlich isotherms with correlation coefficient (r2) very close to unity and langmuir maximum adsorption constant,qm > 1000. the freundlich coefficients relating to overall adsorption capacity,kf (mg g-1) is 197.65 and 396.28 and surface heterogeneity,n is 3.34 and 3.18 for alizarin and fluorescein respectively. the activation energy (ea) of the adsorption process of alizarin and fluorescein on dpa were found to be -8.19 and +21.43 kj mol-1 respectively. the evaluation of the thermodynamic quantities showed that the adsorption process was spontaneous and endothermic.